9 to please him Some editors mark this off by commas. Q's lack of punctuation doubles the flattery: both 'I tell the day, in order to please him, that … ' and 'I tell the day that you are bright only to please him'.

12 twire peep out; 'intr. To look narrowly or covertly; to peer; to peep. Also fig. of a light, etc'. (OED 1; first cited usage)

gild'st the even give a glitter to the evening. Q reads 'guil'st th' eauen'. This could be modernized as 'guilest th' heaven', meaning 'beguile or charm the skies'. 'Gild'st' makes the friend's presence a more obvious substitute for the stars. For a similar moment where Shakespeare seems to have collapsed together guile and gilding see Lucrece l. 1544 and n.

14 length Many editors emend to 'strength'. As Kerrigan notes, this makes the couplet excessively predictable. The couplet works by using repetition to evoke endless labour (day … daily), whilst offsetting the dangerously mimetic tedium so generated by a daring interchange of length and intensity.

This and the following sonnet (linked in a cycle of woe by their opening word) make use of the conventions of complaint: the lover is isolated and apparently deprived of all means of comfort until thoughts of the friend dispel his gloom.